In the field of graphic arts, an image-forming system providing a super-high contrast photographic characteristic, especially one having a sensitivity ("gamma") of 10 or more, is required for satisfactory reproduction of continuous tone images or line images by dot images. For this purpose, a specific developer called a lith-type developer is generally used. The lith developer contains, as a developing agent, hydroquinone and, as a preservative, a sulfite usually in the form of an adduct with formaldehyde at a concentration of not more than 0.1 mol/1, thereby preventing deterioration of the infectious development ability of the developing agent. The lith developer has a serious disadvantage in that it is very susceptible to air oxidation and cannot withstand use for a period of time exceeding 3 days. Increasing the sulfite content of the developer improves its useful life but deteriorates its high-contrast development characteristics.
Known ways to obtain equivalent or substantially equivalent high-contrast photographic characteristics with a stable developer include the use of hydrazine or hydrazide derivatives as described for example in U.S. Pat. Nos. 4,224,401, 4,168,977, 4,166,742, 4,311,781, 4,272,606, 4,211,857 and 4,243,739 all incorporated by reference in their entirety. Use of hydrazine or hydrazide compounds in image formation systems provides super-high contrast and high sensitivity, and also ensures greatly improved stability of the developer against air oxidation as compared to the conventional lith developer because hydrazine (and/or derivative) presence in the film or in the developer permits use of a higher sulfite ion concentration in the developer.
For the light-exposure of certain photographic materials, various light sources such as Helium/Neon lasers and light-emitting diodes have been developed and are in use. To obtain emulsions with sufficient spectral sensitivity at these light frequencies, selected spectral sensitizing dyes have been used. Such emulsions required use of a lith developer.
It would be very desirable to incorporate in such emulsions (or in their developer) one or more of the hydrazides disclosed in U.S. Pat. No. 4,686,167, without decreasing speed below acceptable levels, and without causing unacceptable levels of color staining and "pepper".